Data which goes thru the consensus mechanism is determined in multiple sources.
1.Consensus on the blockchain is built on incentive. The network of computers are all incentivized to tell the truth because they receive a monetary benefit.
What does it mean when we say that in blockchain, consensus determine the truth?
The different nodes agree by consensus on the validity of a transaction. It is a trustless network and the different participants agree on the truth as they are incentivized to come to agreement.
How is this different from how truth is determined in a central database?
In a centralized system, there is one unique source of truth, and trust must be placed in the central authority.
that all nodes on the network can simultaneously verify the validity of a transaction, and allow all parties to behave in a trust-less manner.
on central databases all information is controlled from a centralized authority who could potentially change data if they wanted.
Consensus is a network of computers that come to an agreement to include or not include information on the ledger/blockchain/database. It creates trustlesness and doesnât have one central authority. It involves many to agree and verify. Consensus is achievable through incentives to keep all involved honest.
Blockchain and consensus go hand in hand. Consensus is the act of multiple nodes across the network âagreeingâ whether or not a transaction is valid before it takes place. This is done by verifying through checking the pre-existing blockchain to see if all conditions are met and correct prior to verifying the transaction.
The above example differs from centralized databases by having a mathematical protocol in place to âcheckâ transactions before they take place. In the centralized model, an organization or individual can potentially duplicate (steal) or modify data to induce a desired outcome, usually not a good one.
Teamwork between nodes work together to form a consensus about a transaction which is incentivized
There is no centralized authority and is a trustless, transparent system. The database can intervene but no person can intervene
Consensus determines the truth as the outcome needs to be agreed upon by the network. Consensus removes the need for trust, there is an incentive to be truthful and you can be confident that everyone is telling the truth as it can be verified by checking the network.
In a central database, truth is determined by the central authority/administrator.
Homework on Consensus - Questions
What does it mean when we say that in blockchain, consensus determine the truth?
As the blockchain stores all tx and every node (participant) in the network can check all tx the result of all those checks is the consensus. if a tx is wrong the majority (>50%) will have the same result and the wrong tx will be not processed in the next block.
How is this different from how truth is determined in a central database?
A central DB can not be checked by every node as access may be prohibited. This leaves room for speculationâŚ
100% of nodes must agree on a tx or the network might fork. 
1 What does it mean when we say that in blockchain, consensus determine the truth?
Consensus is determined by what the agreed view is at the time of review. Truth is amde up of a variability of factors but most always established by crowd agreement making up the current reality.
What does it mean when we say that in blockchain, consensus determines the truth?
CONSENSUS determines the truth because once data is accepted in the public ledger, a network of computers must mutually agree that such data/transaction presented is correct to confirm the transaction. The consensus is achieved through a popular mechanism known as PoW 
How is this different from how truth is determined in a central database?
The central database is the complete opposite of the consensus mechanisms of the blockchain. Truth in the central database is determined by an entity/third party application. Is there such a consensus agreement or incentives in the central database like blockchain does? Altered data added to the central database could result in errors and system failures. 
Correct me if Iâm wrong
This is true if you for example try to alter relational data. But you wouldnât really crash the database if you would just change the balance for a user from 0 to 1000000
Consensus is simply the agreement of computers on the network that an addition to the blockchain is correct and belongs on the ledger.
Consensus can only be achieved on a central database by an independent third (or 4th, 5th) party. Even then it still requires trust to believe that the data is true. Given the number of confirmations that are required on a decentralised network (and that they are incentivised!), it ensures the blockchain can verify that data it stores is correct.
What does it mean when we say that in blockchain, consensus determines the truth?
With Consensus, a number of unrelated parties need to agree on a blockchain entry for it to be considered the Truth. They are incentivized with money to do this.
How is this different from how truth is determined in a central database?
Consensus is Trustless verification by independent parties and doesnât require faith in those that create the database entry. Regular central databases can be altered, donât use consensus and require trust in the creator of the database.
Thanks. so either they all agree on the same result or the network has to fork? so what happens if 1 node does not agree. this will not halt the network, right? and it will not cause a fork immediately, right?
thanksâŚ